Not sure if this is the right place to post but when searching for the below issues, this site always comes up and after reading through multiple forums with similar issues and not finding a solution I thought I would post. Any insight you may be able to provide would greatly be appreciated.

1998 Mazda B4000 4.0 V6, Automatic, 4x4, 183,000 Miles

Issue:

Drove to work, 30-mile drive then sat in parking lot idling for approx. 15-30 minutes. No noticeable issues. Typical commute. Went to work. Left for lunch pulled into a local shopping center and as I made the turn, the truck starting revving up then down and bucking/jerking, then it stalled. Cranked a few times but wouldn’t start. Pushed it into a parking spot, called someone for a ride and waited. When they arrived, turned key and started right up, ran fine for several minutes then drove around the lot a few times and still no issue. Decided to head back to work, with help in review mirror. About a mile away the truck started revving up/down, bucking/jerking again. Made it around the corner and stalled again. Cranked a few times same as before but would not start. Towed to local shop who wouldn’t be able to look at for a week. A co-worker offered to look at

The CEL light has not come on through the process. No codes have displayed on multiple OBD2 scanners. No vacuum leaks have been detected.

The following parts have been replaced in stages.

• Fuel Filter Fuel Pump
• Intake Gasket - All Injectors - Spark Plugs (Wires are New)
• Coolant Temperature Sensor x 2 - Oxygen Sensors x 3
• Fan Clutch
• MAF Sensor - IAC Valve
• EGR Valve - Throttle Position Sensor

Between each stage. The truck would crank and start without issue and idle between 800-1000 RPM for what seems to be about an hour. Then the revving begins, up/down between 1000, 1500, 2000, 2500 and 3000 RPM (never over 3000). A few cycles or so of this and eventually it drops below 1000 and stalls. Yet it will crank and start right up. Often resuming the previous. However, if allowed to sit for a few minutes or so it will crank and start and idle right between 800-1000 RPM but eventually it returns to the revving.

The revving always returns. The bucking/jerking is only apparent when driving.

At a loss here. Could it be the PCM, GEM or both? Computer related issue? Short?

 

Emissions issue... EGR Valve Control Solenoid, Canister Purge Solenoid (CPS) or Canister Valve Solenoid (CVS)?

 

I did not replace the EGR Valve Control Solenoid, Canister Purge Solenoid or Canister Valve Solenoid.
I ended up purchasing a new computer and it appears to have solved this issue. Have been driving the truck back and forth to work etc... without issue for the past month.
I called local Mazda dealer, gave the last 8 of VIN and was told that both Mazda and Ford have retired the part. However, tech was able to provide updated part numbers.
Mazda: ZZT818881A
Ford: F87Z12A650AMC
I was able to find a replacement that matched both numbers on Rock Auto. Once it arrived, uninstalled previous and installed reman and as mentioned truck has been running great without any issues.
The part number on previous computer in truck was F87F-12A640-BUA.